Preparation of 2,2{40 -bipyridyl

ABSTRACT

Pyridines are converted into 2,2&#39;&#39;-bipyridyls by treatment with Ziegler catalysts.

Unlted States Patent 1 3,697,534

Waddan et al. 51 Oct. 10, 1972 [54] PREPARATION OF 2,2-BIPYRIDYL [56]References Cited [72] Inventors: Dhafir Yusuf Waddan; Derek Wil- OTHERPUBLICATIQNS liams, both of Manchester, England Gaylord, Reductlon WlthComplex Metal Halldes, In- 1 Asslgnw v Chemwal Industrles tersciencePublishers Pages .1027, 1028, 1033- 1035,

Llmlted, London, England (1956) QD63 R463 C.4 Fieser and Fieser,Reagents For Organic Synthesis, [22] filed 1969 John Wiley & SonsPublishers, Page 1170, (1967) [21] Appl. No.: 862,944 QD262 F5 C.4

Primary Examinr-Alan L. Rotman [30] Forelgn Appllcatlon Priority Data;Attorney cushman, Darby & Cushman Oct. 3, 1968 Great Britain ..47,023/68[57] ABSTRACT U'Sl s s s s s s s s e e s s s s s s e s e e s s s s s s ee [5 l lift. Cl. ment with Ziegler catalysts. [58] Field of Search..260/296 D 4 Claims, No Drawings PREPARATION OF 2,2'-BIPYRIDYL Thisinvention relates to a process for the preparation from pyridines of2,2'-bipyridyls, useful as intermediates for the manufacture ofherbicides.

According to the invention there is provided a process for thepreparation of 2,2'-bipyridyls which comprises treating a pyridine witha Ziegler catalyst as hereinafter defined.

As pyridines there may be used pyridine itself or pyridines containingone or more alkyl groups containing not more than four alkyl carbonatoms altogether and having at least one free position adjacent to thenitrogen atom. The use of alkyl pyridines affords the correspondingalkylated 2,2-bipyridyls. Also other heterocyclic compounds containingthe pyridine nucleus such as quinoline, isoquinoline, lepidine,phenanthridine, acridine or nicotine, may be used. The expressionZiegler catalyst is well-known in the art and indicates a combination ofcompounds from each two classes hereinafter called Classes A and Brespectively and optionally at least one compound from a third classhereinafter called Class C. These classes are as follows CLASS ATransition metal compounds. The term transition metal means a metalwhich in elementary form has an incomplete shell of d or f electrons.These are the elements of atomic numbers 2l29, 39-47 and 71-79inclusive. Of these the preferred metals are cobalt, palladium,ruthenium, platinum, and especially nickel. Compounds of these metalswhich may be used in the combination include oxides, hydroxides,alkoxides, salts (particularly organic acid salts e.g., acetates,propionates, ectoates, benzoates or naphthenates), chelating salts suchas acetylacetonates, complexes containing pior sigma-bonded ligands orallyl groups attached to metal (e.g., bis-cyclopentadienyl and carbonylcomplexes) and complexes of zero valent metals with olefinic and otherdonors, e.g. amines, nitriles, ethers, thiocompounds, phosphines andphosphites.

CLASS B Certain compounds which have a reducing action on the metalcompounds of Class A including metal alkyls or aryls, especially thosein which an alkyl group is directly attached to aluminum, e.g.,triethyl-, tripropyl and triisobutylaluminum, monochlorodiethylaluminum,dichloroethylaluminum, ethoxydiethylaluminum, diisobutylaluminum hydrideand the etherides of these compounds. Other compounds in Class B areorganic compounds of aluminum e.g., aluminum salts of organic acids,organic compounds of lithium, zinc or magnesium (e.g., lithium ethyl,zinc diethyl and magnesium ethyl chloride), compounds such as sodiumbis(ethoxymethoxy) aluminum hydride, and hydrides of alkali metals e.g.sodium hydride or sodium borohydride. Preferred components are thealuminum trialkyls and aluminum ethyldiacetate, aluminum diethylacetate,aluminum triacetate and aluminum diethylacetylacetonate and similaraluminum compounds. Mixtures of two or more compounds from Class B maybe used in the catalyst compositions.

CLASS c Ligands which can co-ordinate with the combination of compoundsof Classes A and B. These include water, ethers, e.g., diethyl ether andtetrahydrofuran; alcohols e.g., ethyl alcohol, methyl alcohol, butylalcohol, phenols, e.g., phenol, p-cresol; amines, e.g., triethylamine,pyridine; phosphines e.g., triphenylphosphine,l,2-bis(diphenylphosphino)ethane; sulphides, e.g., thiodioxane andnitriles. e.g., acetonitrile, benzonitrile.

Ziegler catalysts are made by bringing the components from Classes A andB together, optionally in the presence of a solvent for example ahydrocarbon, e.g., cyclohexane or benzene, or an ether, e.g.,tetrahydrofuran and allowing interaction to take place, either with freeevolution of heat or with cooling. The word combination implies onlythat the components from Classes A and B are materials used to make thecatalyst and carries no implication regarding the chemical structure ofthe catalyst. The optional component from Class C may be added before orafter the components from Classes A and B are brought together.

The component from Class A and Class B may suitably be used in a molarratio of 0.2-l0zl, and preferably in a molar ratio of about 1:2. Thecomponents from Class C, when used, may be present in molar ratio withrespect to the component from Class B of 02-10: 1 and preferably about1:2.

The process may conveniently be carried out by mixing the solution ofZiegler catalyst, obtained by combination of the components from ClassesA and B together, with a pyridine, and reacting the mixtures, ifnecessary at superatmospheric pressure, at a temperature between 0 and300 preferably at a temperature between and 200 C. The bipyridyl may beisolated by removal of unreacted pyridine by distillation and eitherfurther distillation of the high boiling residue, or extraction of theresidue with a solvent such as petroleum ether. Unreacted pyridine canbe recovered by distillation and reused in the process. The reaction maybe carried out batchwise or continuously.

If desired the process may be carried out under an atmosphere ofhydrogen.

The invention is illustrated but not limited by the following examplesin which all parts and percentages are by weight unless otherwisestated.

EXAMPLE 1 Aluminumtriisobutyl (1.1 ml. of 50 percent solution inbenzene) is added to 0.1877 g. of nickel acetate followed by 10 ml. ofpyridine. The mixture is kept at 165 C. for 8 hours. 2,2'-bipyridyl isisolated by removal of unreacted pyridine by distillation and furtherdistillation of 2,2'-bipyridyl from the residue at a boiling point of269-70 C. The sample of bipyridyl thus obtained (0.35 g.) had a meltingpoint of 69 C.

EXAMPLE 2 Aluminumtriisobutyl (3.7 ml. of 50 percent solution inbenzene) is added to 0.65 g. of nickel acetate followed by 15 ml. ofpyridine. The mixture is charged to an autoclave and kept at C. for 6hours under a pressure of 30 p.s.i. of hydrogen. Bipyridyl (0.5 g.) isisolated by the procedure described in Example 1.

EXAMPLE 3 aluminumtriisobutyl (3.4 ml. of 50 percent solution inbenzene) is added to 0.596 g. of nickel acetate followed by 15 ml. ofpyridine. The mixture is kept at 150 C., for 6 hours. Bipyridyl isisolated by the procedure described in Example 1.

EXAMPLE 4 Aluminumtriisobutyl (4 ml. of 50 percent solution in n-hexane)is added to 0.855 g. of palladium-acetate followed by 10 ml. ofpyridine. The mixture is kept at 1 15 C. for 4 hours. Bipyridyl (0.6 g.)is isolated by the procedure described in Example 1.

EXAMPLE 5 Aluminumtriethyl (0.44 ml. of 50 percent solution in benzene)is added to nickel acetate (0.137 g.) followed by 0.1 g. of aluminumdiacetate and 20 ml. of pyridine. The mixture is kept at 1 15 C. for 70hours. 0.58 g. of 2,2-bipyridyl is obtained. The unreacted pyridine isrecovered.

EXAMPLE 6 Aluminumtriethyl (0.33 ml. of 50 percent solution in benzene)is added to 0.1 g. of nickel acetate followed by 0.2 g. of ethylaluminumdiacetate and 20 ml. of pyridine. The mixture is kept at 1 15 C. for 160hours. 0.95 g. of 2,2-bipyridyl is obtained. The unreacted pyridine isrecovered.

EXAMPLE 7 Aluminumtriethyl (0.33 ml. of 50 percent solution in benzene)is added to 0.1 g. of nickel acetate followed by 0.2 g.of ethylaluminumdioctoate and 20 ml. of pyridine. The mixture is kept at 115 C. for 20hours. 0.54 g. of 2,2'-bipyridyl is obtained. The unreacted pyridine isrecovered.

EXAMPLE 8 Aluminumtriisopropyl (3.65 ml. of 50 percent solution inbenzene) is added to 0.6504 g. of nickel acetate followed by 15 ml. ofpyridineThe mixture is kept at 140 C. for 6 hours under an initialpressure of 30 lb./in of hydrogen. 2,2'-Bipyridyl (0.5 g.) is isolatedby the procedure described in Example 1.

EXAMPLE 9 Aluminumtriisobutyl (5.1 mlof 50 percent solution in n-hexane)is added to 0.8980 g. of nickel acetate followed by 0.5 ml. oftriethylamine and. 15 ml. of pyridine. The mixture is kept at 115 C. for5 hours. 0.144 g. of 2,2'-bipyridyl is obtained.

EXAMPLE l Aluminumtriethyl (2.6 ml. 50 percent solution in nhexane) isadded to 0.8514 g. of nickel acetate followed by 1 ml. oftetrahydrofuran and ml. of pyridine. The mixture is kept at 150 C. for 6hours. 0.047 g. of 2,2 -bipyridyl is obtained.

EXAMPLE 11 n-Butylbromide (1.3 ml. in 1 ml; ether) is added to magnesium(0.3 g. in 5 ml. ether). 0.4560 g. of nickel acetate is added to thismixture followed by ml. of

pyridine. The mixture is kept at 115 C. for 4 hours.

The presence of 2,2'-bipyridyl in the product was confirmed by U.V.spectrometry.

EXAMPLE 12 Aluminumtriisobutyl (4.5 ml. of 50 percent solution inn-hexane) is added to 1.0323 g. of cobaltous acetate followed by 15 ml.of pyridine. The mixture is kept at 1 15 C. for 3% hours. U.V. analysisshowed the presence of 2,2-bipyridyl in the reaction product.

EXAMPLE 13 Aluminumtriisobutyl (4 ml. of 50 percent solution inn-hexane) is added to 0.8551 g. of palladiumacetate followed by 10ml. ofpyridine..The mixture is kept at 1 15C. for 4 hours. 0.4 g. of2,2'-bipyridyl is obtained. The unreacted pyridine is recovered.

EXAMPLE 14 Sodium dihydrobis( 2-methoxyethoxy)aluminate (1.3 ml. ofpercent solution in benzene) is added to 0.4032 g. of nickel acetatefollowed by 10 ml. of pyridine. The mixture is kept at C. for 23 hours.0.226 g. of 2,2-bipyridyl is obtained.

EXAMPLE 15 Sodium dihydrobis( 2-methoxyethoxy )aluminate (0.8 ml. of 70percent solution in benzene) is added to 0.2362 g. of nickel acetatefollowed by 20 ml. of pyridine. The mixture is kept at 1 15 C. for 24hours in a hydrogen atmosphere. 0.168 g. .of 2,2'-bipyridylis obtained.

EXAMPLE l6 Lithium aluminum hydride (0.2 g. in ether) is added to 0.34g. of nickel acetate followed by 20 ml. of pyridine. The mixture is keptat 115 C. for 27 hours. 0.11 g. of 2,2-bipyridyl is obtained.

EXAMPLE 17 0.7 ml. of isobutanol is added to aluminumtriisobutyl (3.7ml. of 50 percent solutionin n-hexane). The resulting aluminumisobutoxydiisobutyl is added to 0.649 g. of nickel acetate followed by20 ml. 1 of pyridine. The mixture is kept at 115 C. for 7 hours. 0.24 g.of 2,2'-bipyridyl is obtained.

EXAMPLE l8 Aluminumtriethyl (0.7 ml. in 50 percent solution of n-hexane)is added to 0.2874 g. of nickel acetate followed by 20 ml. of pyridine.The mixture is kept at 1 15 C. for 7 hours in an atmosphere of hydrogen.0.177 g. of 2,2-bipyridyl is obtained.

EXAMPLE 19 EXAMPLE 20 Aluminumtriethyl (0.2 ml. 50 percent solution intoluene) is added to nickel benzoate (0.1075 g.) followed by aluminumethyldipropionate (0.24 g. in 3 ml. of toluene) and pyridine (20 ml.).The mixture is kept at 115 C. for 22 hours. 0.2 g. of 2,2-bipyridyl isobtained.

EXAMPLE 21 Aluminumtriethyl (0.163 ml. is added to nickelacetate (0.1008g. in 0.5 ml. of toluene) followed by aluminum ethyl bis(phenylacetate)(0.4 g. in 0.5 ml. of toluene) and pyridine (20 ml). The mixture is keptat 1 C. for 45 hours. 0.25 g. of 2,2'-bipyridyl is obtained.

EXAMPLE 22 EXAMPLE 23 Aluminumtriethyl (0.34 ml. of 50 percent solutionin toluene is added to nickelacetate (0.1038 g.) and Y- picoline (0.1ml.) followed by pyridine ml.). The mixture is kept at 1 15 C. for 18hours. 0.8 g. of 2,2- bipyridyl is obtained.

EXAMPLE 24 Aluminumtriethyl (0.35 ml. of 50 percent solution in toluene)is added to nickel acetate (0.1101 g.) and tetrahydrofuran (1 ml.)followed by aluminum ethyldiacetate (0.2g.) and pyridine (20 ml.) Themixture is kept at reflux temperature for 48 hours. 0.008 g. of2,2'-bipyridy1 is obtained.

EXAMPLE 25 Aluminumtriethyl (3.23 ml. of 50 percent solution in.

toluene) is added to nickelacetate (1.00 g. followed by aluminumethyldipropionate (3.84 g.) and pyridine (200 ml. The mixture is kept at1 15 C. for 186 hours. 9.3 g. of 2,2'-bipyridyl is isolated bydistillation.

EXAMPLE 26 Aluminumtriisobutyl (2 ml. of 50 percent solution inn'hexane) is added to chromium diacetate (0.336 g.)

followed by pyridine (20 ml.) The mixture is kept at 1 15 C. for 2%hours. The presence of 2,2'- -bi-pyridyl is conformed by U.V.spectrometry.

EXAMPLE 27 Aluminumtriethyl (0.33 ml. of 50 percent solution inn-hexane) is added to nickel acetate (0.1007 g.) followed by aluminumethyl dioctoate (0.2 g.) and pyridine (20 ml.). The mixture is kept atC. for 117 hours. 0.438 g. of 2 ,2- b i p yridyl is obtained.

EXAMPLE 2.8

Aluminumtriethyl (0.35 ml. of 50 percent solution in toluene) is addedto nickelacetate (0.1089 g.) followed by aluminum ethyldiacetylacetonate (0.45 ml. of 50 percent solution in toluene) andpyridine (20 ml.). The mixtures is kept at 115 C. for 66 hours. 0.264 g.of 2,2'-bipyridy1 is obtained.

We claim:

1. A process for the preparation of 2,2'-bipyridyl which consistsessentially of treating a pyridine with a Ziegler catalyst which is acombination of (A) a transition metal compound selected from the groupconsisting of an oxide, hydroxide, alkoxide, carboxylic acid salt andacetylacetonate, carbonyl and bis-cyclopentadienyl complexes of nickel,ruthenium, palladium, platinum, cobalt and chromium and (B) a reducingagent for said compound (A), said agent (B) being selected from thegroup consisting of aluminum, zinc, magnesium and lithium alkylcompounds in which the alkyl is lower alkyl attached directly to themetal and alkali metal hydrides, at a temperature between 0 C and 300 C.

2. A process as claimed in claim 1 wherein the transition metal compounds nickel, chromium, cobalt or palladous acetate, nickel benzoate ornickel acetylacetonate and the reducing agent is an aluminum trialkylwherein the alkyl contains up to four carbon atoms.

3. A process as claimed in claim 1 wherein the molar ratio of thetransition metal compound to that of the reducing agent is 0.2 10 1.

4. A process as claimed in claim 1 wherein the Ziegler catalyst containsa ligand for the combination of the transition metal compound andreducing agent, said ligand being selected from the group consisting ofwater, diethylether, tetrahydrofuran, ethyl alcohol, methyl alcohol,butyl alcohol, phenol, p-cresol, triethylamine, pyridine,triphenylphosphine, 1,2- bis(diphenylphosphino)ethane, thiodioxane,acetonitrile and benzonitrile.

2. A process as claimed in claim 1 wherein the transition metal compounds nickel, chromium, cobalt or palladous acetate, nickel benzoate ornickel acetylacetonate and the reducing agent is an aluminum trialkylwherein the alkyl contains up to four carbon atoms.
 3. A process asclaimed in claim 1 wherein the molar ratio of the transition metalcompound to that of the reducing agent is 0.2 - 10 :
 1. 4. A process asclaimed in claim 1 wherein the Ziegler catalyst contains a ligand forthe combination of the transition metal compound and reducing agent,said ligand being selected from the group consisting of water,diethylether, tetrahydrofuran, ethyl alcohol, methyl alcohol, butylalcohol, phenol, p-cresol, triethylamine, pyridine, triphenylphosphine,1,2-bis(diphenylphosphino)ethane, thiodioxane, acetonitrile andbenzonitrile.